Pin SciPy to 1.6.3 on Mac (take 2) (#64922)
Summary:
It's already pinned by via docker install on Linux
`scipy.stats.`[`poission`|`geom`|`binom`] returns quite different results between 1.6.x and 1.7+ versions of SciPy, which results in several distributions tests failing accuracy thresholds
Reland of https://github.com/pytorch/pytorch/pull/64844 but limited to just Mac platform
Followup PR for Windows are coming as well
Pull Request resolved: https://github.com/pytorch/pytorch/pull/64922
Reviewed By: janeyx99
Differential Revision: D30901257
Pulled By: malfet
fbshipit-source-id: 0543e7bae9d3bbeb8b6be7b3ecf605880f97665f
